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STOCKHOLM : 2014 WINNER

Biochar: Engaging Citizens in the Fight Against Climate Change

  • 917,000

    Population (2015)
  • €51,560

    GDP per capita (2013)
  • Swedish

    Official language
  • Indirectly elected mayor (four-year term)

    Type of government
  • Additional facts

    • 8 in 10 residents desire to be more active in the fight against climate change
  • • The city expects using biochar in plant beds will increase plant growth by up to 30% in the Swedish climate and up to 200% in more favorable conditions
  • • One ton of biochar is expected to sequester 3.6 tons of carbon dioxide

The Problem

Climate change is one of the greatest threats of our era. Stockholm aims to become a fossil free city by 2040, and citizens want to help—with 80 percent of them saying they want to be more active in the fight against climate change. Still, the city lacked solutions that engaged residents or provided them with a way to directly contribute to the city’s goal.

The Innovation

Stockholm’s Biochar Project aims to reduce carbon emissions by enabling citizens to be part of carbon sequestration. Residents will provide plant waste to the city, which will produce biochar – a charcoal-like product that can sequester carbon in soil for thousands of years. Biochar, when placed in plant beds, improves soil structure, encourages plant growth, and helps to purify storm water run-off. Additionally, a by-product of the biochar production process is pyrolysis gas, which will be used to generate energy for the city’s district heating system. While there are examples of biochar use across Europe, Stockholm is implementing the first large-scale collaboration between local authorities and citizens in the generation of the product.

The Impact

Stockholm’s first physical biochar plant opened in March 2017—and four more are planned to be completed by the end of 2018. The City anticipates these five plants will produce 7,000 tons of biochar by 2020, sequestering 25,200 tons of CO2 (the equivalent of taking 3,500 cars off the road) and producing a corresponding 25,200 megawatt hours of energy. Click here to learn more about the biochar life cycle.

The city has already received nearly 100 requests from cities and organizations that are interested in replicating the program. As a result, the team has published a replication manual and checklist for reference.


  • Additional facts

    • 8 in 10 residents desire to be more active in the fight against climate change
  • • The city expects using biochar in plant beds will increase plant growth by up to 30% in the Swedish climate and up to 200% in more favorable conditions
  • • One ton of biochar is expected to sequester 3.6 tons of carbon dioxide

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